The present invention relates to a manufacturing method of a semiconductor device, and in particular, to a method of dry etching an insulating film.
In manufacturing processes of semiconductor devices, such as advanced microcomputer products, advanced SOC (System-on-a-Chip) products, and sophisticated liquid crystal drivers, ArF photolithography by an ArF excimer laser and a damascene process in which a wiring layer is embedded and formed in an insulating layer are used.
When a wiring layer is formed in a damascene process, a wiring trench (trench) is formed by dry etching an insulating layer, such as a silicon oxide film or a low dielectric constant film (Low-k film), with the use of an ArF resist as a mask.
Mixed gas, such as CF4/CHF3, CF4/CH2F2/N2, CF4/C4F6, or CF4/C4F8, is used as etching gas in the dry etching.
For example, a capacitively-coupled oxide film dry etching apparatus by two high-frequency waves is used as the dry etching apparatus. As these high-frequency waves, it is typical to apply a wave of 60 MHz frequency to the upper electrode and a wave of 2 MHz frequency to the lower electrode.
For example, the technique disclosed in Patent Document 1 (Japanese Unexamined Patent Application Publication No. 2001-274141) is cited as a background technique for the present technical field. Patent Document 1 discloses a manufacturing method of a semiconductor device, in which an insulating film including a silicon-based material is etched by mixed gas of CHF3/CO/CF4.
Patent Document 2 (Japanese Unexamined Patent Application Publication No. 2011-119310) discloses a method of etching a thin film including a semiconductor, a dielectric, or a metal by using etching gas containing CHF2COF.
Patent Document 3 discloses an etching agent containing CaFbHc. Herein, it is specified that: each of a, b, and c in the CaFbHc represents a positive integer (excluding a=3, b=4, c=2); and the relationships of 2≦a≦5, c<b≧1, 2a+2>b+c, and b≦a+c are satisfied.